"To be an adult, you need to know when it is apropriate to be childish"
"Never paint the devil on the wall, unless he stands in the hallway, so make sure you have some paint at home"
"Honesty lasts longest"
The first advice here basically boils down to "remember to have fun in a responsible manner", I like the original phrasing better as is more fun and also implies as shitload more knowledge.
The second advice is a modified version of a Swedish saying, it boils down to, "don't expect the worst, but if it happens, take notes and learn, oh and you should have a pen and notebook at home". I like this as well as it again tells you to relax, but learn from mistakes and be prepared to learn from them.
The third advice is just common sense, life just gets so much easier if you act and speak honestly, this obviously doesn't mean to be brutaly honest or blatantly selfish as long as you are honest. But rather avoid situations that would require you to lie.
EDIT:
I just thought about another peice of advice:
"If you have nothing to hide, then you can't be trusted"
We all have secrets, some are just embarrasing, others can destroy lives, stating that you have nothing to hide is one of the worst ways to try and gain trust, since it means one of two things:
You are a liar, as previously stated everyone has things to hide, so you are just plain lying.
You won't keep a secret, if asked you will tell others priveleged information given to you.